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<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><strong class="selflink"><span class="t-lines"><span>qsort</span></span></strong></div></div></td></tr>
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<td> <div>Defined in header <code>&lt;stdlib.h&gt;</code>
 </div>
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<td class="t-dcl-nopad"> <div><span class="mw-geshi c source-c"><span class="kw4">void</span> qsort<span class="br0">(</span> <span class="kw4">void</span> <span class="sy2">*</span>ptr, <a href="../../cpp/types/size_t.html"><span class="kw100">size_t</span></a> count, <a href="../../cpp/types/size_t.html"><span class="kw100">size_t</span></a> size,<br>
            <span class="kw4">int</span> <span class="br0">(</span><span class="sy2">*</span>comp<span class="br0">)</span><span class="br0">(</span><span class="kw4">const</span> <span class="kw4">void</span> <span class="sy2">*</span>, <span class="kw4">const</span> <span class="kw4">void</span> <span class="sy2">*</span><span class="br0">)</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td class="t-dcl-nopad">  </td>
<td class="t-dcl-nopad">  </td>
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<p>Sorts the given array pointed to by <code>ptr</code> in ascending order. The array contains <code>count</code> elements of <code>size</code> bytes. Function pointed to by <code>comp</code> is used for object comparison.
</p>
<p>If <code>comp</code> indicates two elements as equivalent, their order is undefined.
</p>
<table id="toc" class="toc"><tr><td>
<div id="toctitle"><h2>Contents</h2></div>
<ul>
<li class="toclevel-1 tocsection-1"><a href="qsort.html%23Parameters"><span class="tocnumber">1</span> <span class="toctext">Parameters</span></a></li>
<li class="toclevel-1 tocsection-2"><a href="qsort.html%23Return_value"><span class="tocnumber">2</span> <span class="toctext">Return value</span></a></li>
<li class="toclevel-1 tocsection-3"><a href="qsort.html%23Example"><span class="tocnumber">3</span> <span class="toctext">Example</span></a></li>
<li class="toclevel-1 tocsection-4"><a href="qsort.html%23See_also"><span class="tocnumber">4</span> <span class="toctext">See also</span></a></li>
</ul>
</td></tr></table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Parameters">edit</a>]</span> <span class="mw-headline" id="Parameters">Parameters</span>
</h3>
<table class="t-par-begin">


<tr class="t-par">
<td>  ptr
</td>
<td> -
</td>
<td>  pointer to the array to sort
</td>
</tr>
<tr class="t-par">
<td>  count
</td>
<td> -
</td>
<td>  number of element in the array
</td>
</tr>
<tr class="t-par">
<td>  size
</td>
<td> -
</td>
<td>  size of each element in the array in bytes
</td>
</tr>
<tr class="t-par">
<td>   comp
</td>
<td> -
</td>
<td>  comparison function which returns ​a negative integer value if the first argument is <i>less</i> than the second, <br>
<p>a positive integer value if the first argument is <i>greater</i> than the second and zero if the arguments are equal.<br>
The signature of the comparison function should be equivalent to the following:
</p>
<p><span class="t-cc"><span class="mw-geshi c source-c"> <span class="kw4">int</span> cmp<span class="br0">(</span><span class="kw4">const</span> <span class="kw4">void</span> <span class="sy2">*</span>a, <span class="kw4">const</span> <span class="kw4">void</span> <span class="sy2">*</span>b<span class="br0">)</span><span class="sy4">;</span></span></span>
</p>
<p>The function must not modify the objects passed to it.
</p>
<p>​
</p>
</td>
</tr>
</table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Return value">edit</a>]</span> <span class="mw-headline" id="Return_value">Return value</span>
</h3>
<p>(none)
</p>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Example">edit</a>]</span> <span class="mw-headline" id="Example">Example</span>
</h3>
<div class="t-example">
<p> The following code sorts an array of integers using <code>qsort()</code>
 </p>
<div class="t-example-live-link"><div class="coliru-btn coliru-btn-run-init">Run this code</div></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="c source-c"><pre class="de1"><span class="co2">#include &lt;stdio.h&gt;</span>
<span class="co2">#include &lt;stdlib.h&gt;</span>
 
<span class="kw4">int</span> compare_ints<span class="br0">(</span><span class="kw4">const</span> <span class="kw4">void</span><span class="sy2">*</span> a, <span class="kw4">const</span> <span class="kw4">void</span><span class="sy2">*</span> b<span class="br0">)</span>
<span class="br0">{</span>
    <span class="kw4">const</span> <span class="kw4">int</span> <span class="sy2">*</span>arg1 <span class="sy1">=</span> a<span class="sy4">;</span>
    <span class="kw4">const</span> <span class="kw4">int</span> <span class="sy2">*</span>arg2 <span class="sy1">=</span> b<span class="sy4">;</span>
 
    <span class="kw1">return</span> <span class="sy2">*</span>arg1 <span class="sy2">-</span> <span class="sy2">*</span>arg2<span class="sy4">;</span>
<span class="br0">}</span>
 
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
<span class="br0">{</span>
    <span class="kw4">int</span> i<span class="sy4">;</span>
    <span class="kw4">int</span> ints<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="br0">{</span> <span class="sy2">-</span><span class="nu0">2</span>, <span class="nu0">99</span>, <span class="nu0">0</span>, <span class="sy2">-</span><span class="nu0">743</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span> <span class="br0">}</span><span class="sy4">;</span>
    <span class="kw4">int</span> size <span class="sy1">=</span> <span class="kw4">sizeof</span> ints <span class="sy2">/</span> <span class="kw4">sizeof</span> <span class="sy2">*</span>ints<span class="sy4">;</span>
 
    qsort<span class="br0">(</span>ints, size, <span class="kw4">sizeof</span><span class="br0">(</span><span class="kw4">int</span><span class="br0">)</span>, compare_ints<span class="br0">)</span><span class="sy4">;</span>
 
    <span class="kw1">for</span> <span class="br0">(</span>i <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> i <span class="sy1">&lt;</span> size<span class="sy4">;</span> i<span class="sy2">++</span><span class="br0">)</span> <span class="br0">{</span>
        <a href="../io/fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"%d "</span>, ints<span class="br0">[</span>i<span class="br0">]</span><span class="br0">)</span><span class="sy4">;</span>
    <span class="br0">}</span>
 
    <a href="../io/fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"<span class="es1">\n</span>"</span><span class="br0">)</span><span class="sy4">;</span>
 
    <span class="kw1">return</span> <a href="../program/EXIT_status.html"><span class="kw493">EXIT_SUCCESS</span></a><span class="sy4">;</span>
<span class="br0">}</span></pre></div></div>
<p>Output:
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="text source-text"><pre class="de1">-743 -2 0 2 3 4 99</pre></div></div> 
</div>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: See also">edit</a>]</span> <span class="mw-headline" id="See_also">See also</span>
</h3>
<table class="t-dsc-begin">

<tr class="t-dsc-sep">
<td colspan="2">
</td>
</tr>
<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="bsearch.html" title="c/algorithm/bsearch"> <span class="t-lines"><span>bsearch</span></span></a></div></div>
</td>
<td>   searches an array for an element of unspecified type <br> <span class="t-mark">(function)</span> 
</td>
</tr>

<tr class="t-dsc-sep">
<td colspan="2">
</td>
</tr>
<tr class="t-dsc">
<td colspan="2"> <div class="t-dsc-see">
<span><a href="../../cpp/algorithm/qsort.html" title="cpp/algorithm/qsort">C++ documentation</a></span> for <span class="t-dsc-see-tt"><span>qsort</span></span>
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